Earlier quoted context omitted.
That is type stripping and is incompatible with syntax that requires transpilation, so it is not native TypeScript support.
Isn't that mostly just enums? Is there anything else that doesn't run as valid JS if you strip the types (and maybe some other extra keywords)out? Genuine question, in my head there's not much, but TS has a few weird corners I maybe haven't used
I'm using it in my projects with no issues.